This document discusses different types of electric motors used in electric vehicles. It begins with an introduction to electric vehicles and their evolution. It then describes conventional DC motors, brushed DC motors, and brushless permanent magnet DC motors. The last type is discussed in detail, including its construction, working, methods to improve performance like hall sensors and optical encoders, advantages and disadvantages. The document concludes with a brief history of electric vehicles.
2. INTRODUCTION
• ELECTRIC VEHICLES ARE AUTOMOBILE ,WHICH ARE
POWERED BY ELECTRIC MOTOR AND ELECTRIC
ENERGY.
• THE DEVELOPMENT OF THE ELECTRIC VEHICLES IS A
VERY PERSPECTIVE AND IMPORTANT PROCESS.
4. Conventional DC Motors
• Converts electrical energy to mechanical energy
• Principle- When a current carrying conductor placed in a
magnetic field experiences a force
• Stator is made up of forced steel with inward projected poles
and poles carry field windings and rotor is of silicon steel
stampings
6. Permanent magnet DC motor
• Construction of PMDC is similar to conventional dc motor
• Stator poles are replaced by suitable permanent magnets
• No need to have field windings .
7. Brushless Permanent Magnet DC Motor
• Brushless DC electric motor also known as electronically commutated
motors (ECMs, EC motors) are synchronous motors that are powered by
a DC electric source via an integrated inverter/switching power supply,
which produces an AC electric signal to drive the motor .
– magnetic fields generated by the stator and rotor rotate at the same
frequency and no slip.
• The stator consists of several coils which current is led through Creating a
magnetic field that makes the rotor turns .
8.
9. Construction of BLDC
• It consist of two parts mainly stator & rotor
Stator
Stator is made up of silicon steel stampings with slots.
The slots are accomodated armature windings.
This winding is wound with specified no.of poles(even number).
This winding connected a dc supply through a power electronic
switching circuits ( inverter circuits) .
10. Rotor
Rotor is of permanent magnet
no of poles on rotor is same as that of stator
Rotor shaft carries a RPS (Rotor position sensor) and it
provides information about the position of shaft at any
instant to the controller which sends signal to the
electronic commutator .
The electronic commutator function is same as that of
mechanical commutator in DC motor
13. Working Of BLDC Motor
• The rotor and stator of a BLDC motor are
shown in the fig . It is clear that, the rotor
of a BLDC motor is a permanent magnet.
14. The stator has a coil arrangement, as illustrated; The
internal winding of the rotor is illustrated in the Fig(core
of the rotor is hidden here). The rotor has 3 coils,named
A, B and C.
Out of these 3 coils, only one coil is illustrated in the Fig
for simplicity. By
applying DC power to the coil, the coil will energize and
become an electromagnet .
15. The operation of a BLDC is based on the simple force
interaction between the permanent magnet and the
electromagnet. In this condition, when the coil A is
energized, the opposite poles of the rotor and stator are
attracted to each other (The attractive force is shown in
green arrow). As a result the rotor poles move near to
the energized stator.
16. As the rotor nears coil A, coil B is energized. As the rotor nears coil B, coil C
is energized. After that, coil A is energized with the opposite polarity . This
process is repeated, and the rotor continues to rotate. The DC current required
in the each coil is shown in the following graph.
17. Improving The BLDC Performance
Unlike a brushed DC motor, the commutation of BLDC motor is
controlled electronically.
It is important to know the rotor position in order
to understand which winding will be energized
following the energizing sequence.
Rotor position is sensed by different ways some
of them are
1) Hall sensors 2) Optical encoders
18. Hall Sensors
When a magnetic field applied to a system with
electric current a hall voltage Perpendicular to the
field and to current is generated.This was discovered
by Edwin Hall in 1879.
19. Advantages
• Increased Reliability & Efficiency
• Longer Life
• Elimination of Sparks from Commutator
• Reduced Friction
• Faster Rate of Voltage & Current
22. HISTORY OF THE ELECTRIC VEHICLE
• THE HISTORY OF THE ELECTRIC VEHICLE BEGAN IN THE MID-19TH
CENTURY.
• 1835: THOMAS DAVENPORT BUILDS THE FIRST PRACTICAL ELECTRIC
VEHICLE.
• IN 1955 WILLIAM G.COBB OF THE GENERAL MOTORS CORP.
DEMONSTRATES HIS 15-INCH LONG “SUNMOBILE”, THE WORLD’S
FIRST SOLAR POWERED AUTOMOBILE.
•
